1. Field of the Invention
The invention relates to a method of patterning a top coating on a substrate, which top coating is provided on a relatively hard substrate and, while being masked by a mask, is exposed to a stream of kinetic particles.
2. Description of the Related Art
The invention particularly relates to such a method in which the top coating is patterned by means of (powder) spraying. As an alternative to a frequently isotropic etching treatment for patterning the top coating, (powder) spraying is generally quicker and has the additional advantage that the material of the top coating is more directionally taken off so that a sharper and better defined pattern can be obtained.
By using a relatively hard substrate as a base, i.e. a substrate which is harder than its top coating and is thus resistant to the stream of kinetic particles, the process automatically stops where the top coating has been removed over its entire thickness and the underlying substrate is reached so that the method should in principle be relatively insensitive to local process fluctuations.
Nevertheless, local deviations in the ultimate pattern of the top coating are still found in practice when, for example a conventional (powder) spraying process is used. Particularly, the ultimate pattern appears to be locally attacked at its base and has sometimes even entirely disappeared locally.